In a recent interview with Variety Stallone revealed that he doesn't want to play the character of John Rambo again:
“The heart’s willing, but the body says, ‘Stay home!,’” Stallone, 69, explained in this week’s cover story. “It’s like fighters that go back for one last round and get clobbered. Leave it to someone else.
”Stallone noted that he was content with where 2008’s “Rambo IV” left the character, which he first played in 1982. “You know when you realize there’s nothing more to pull out?” Stallone says. “As an action film, I was very satisfied that it dealt with the Burmese situation. It had one foot in a current event, the longest civil war in history, 65 years at that time. It was so brutal, which civil war is, I was shocked they even gave me an R-rating. I didn’t want to compromise. I said, ‘This is probably going to be the last decent film of this genre that I’m going to do as a solo act.’ When that was accomplished, I never felt the same willingness to do it again.”He added: “There’s nothing left. When they asked me to do another ‘Rambo,’ I said, ‘If I can’t do better than I did last time, and I can’t, then why’?”
He’s also not involved in the “Rambo” TV series, which is in development at Fox and focuses on the character’s son. “I don’t want to cast aspersions,” Stallone said, “but it’s delicate to try to replace a character with his son. I’ve seen the son of Flicka, the son of Tarzan, the son of King Kong, the son of Godzilla. It’s a very difficult premise.”
"As for his non-“Rocky” career, Stallone is more ambivalent about continuing as an action star. He hopes that “Creed” finally leads the way to more dramatic roles. “I had never, ever thought of myself as an action person,” he says. “I’m just not that athletic. I’m not naturally a mesomorph. I’m actually kind of thin. But I do like the physical challenge.” He adds that shooting tenptole action movies is physically grueling. “I never got tremendous fulfillment from it. Because it becomes a tug of war between exasperation and exhaustion. Very rarely does it all go well. It’s kind of like one of those triathlons.”
We also have a great Stallone interview from Deadline, it's too long to post here but well worth reading.